Solid organ transplant recipients are at an increased risk for developing bladder cancer compared to the general population. Kidney transplant recipients (KTR) with a previous history of BK polyomavirus viremia have an even further increased risk, and the involvement of this virus in bladder carcinogenesis has been speculated for years. Only through recent advances in sample processing and next-generation sequencing has it become more evident that this virus plays a role in at least a small subset of cancers, but the exact nature and extent of this involvement is unclear. However, previous studies have been limited by number of patients or experimental approach. We have collected a cohort of 47 KTRs who have gone on to develop urinary bladder cancer. So far, we have successfully extracted RNA and DNA and performed total RNA and whole genome sequencing. Early data from this project has confirmed the increased involvement of BK polyomavirus in this subset of cancer. We have also identified HPV DNA and transcripts within some of these tumors. On top of the virus-focused analysis, we are also asking what are the differences in the biology of tumors that develop in a weakened immune system versus those that are immunocompetent and what does this mean for the applicability of emerging immunotherapies. Lastly, we are applying these sample technologies to sebaceous carcinoma, which is also at a dramatically increased incidence in immunosuppressed patients and loosely tied to infection with HPV16.